EARNINGS PER SHARE - Basic earnings per share of common stock (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Basic and diluted earnings per share:
Net income	$ 268,384	$ 135,025
Weighted average common shares outstanding (in shares)	2,829,375	2,816,518
Basic and dilutive net income per share	$ 0.09	$ 0.05
Options outstanding	0	0